This new R01 application is submitted in response to PA-08-192 Geographic and Contextual Influences on Energy Balance-Related Health Behaviors. The project proposes multilevel, longitudinal evaluation of obesity related contexts and resulting outcomes (i.e., obesity related behaviors) and impacts (i.e., obesity related endpoints) using the National Health and Nutrition Examination Study (NHANES). The National Center for Health Statistics has recently made available for analysis the georeferenced NHANES to approved researchers. As approved research, the project is organized around characterizing the various food and physical activity environments at the neighborhood and community levels for Continuous NHANES participants in the five surveys conducted and available since 1999 (i.e., NHANES 1999-2000, 2001-2002, 2003-2004, 2005-2006, 2007-2008). By locating NHANES survey respondents within their respective neighborhoods (e.g., census tracts) and political jurisdictions (e.g., census place) and characterizing these locations in terms of the food and physical activity environments the many strengths of the NHANES can be brought to bear to evaluate a number of outstanding issues in the obesity literature.